Re: [Qemu-devel] [PATCH 2/3] ramfb enhancement

[Hou Qiming]

> Only allow one resolution change per guest boot, which prevents a

> > crash when the guest writes garbage to the configuration space (e.g.
> > when rebooting).
>
> Hmm?  Did you see that happen in practice?
> It is not easy to write to fw_cfg by accident ...
>
>
Yes, this does happen in practice. It's observed in KVMGT setups by another
github user and me, when the guest Intel driver loads or when the guest
reboots. Link:
https://github.com/intel/gvt-linux/issues/23#issuecomment-483651476

Now that you mentioned it, I start to feel that it's not accidental. A
closer look at the "garbage" in that post shows that the overwriting
content are valid resolution values in the wrong endian. It could be a
misguided attempt to "resize ramfb" by the guest Intel driver.

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I'll fix the addr / length thing and remove the test part in vfio-pci in V2.

Qiming